1971 50 hp 4 cylinder stalling issue. milky liquid on plug

[oldyeller2011]

would idle fine on muffs, but when got into water after a good stretch it would not want to start back up, and when putting it into gear would stall out right away. After getting it home i looked at the plugs and checked compression. Im getting 130 120 120 110 (was 105 on last cylinder before i took it on water). Before i noticed the milky on the plug the battery died so i thought maybe the stator was bad, but pretty sure it was just a bad battery because i replaced it and it seemed better other then this issue.

I have did research and it looks like the lower seal is going bad? how serious is this? i wont be starting the engine until this is replaced.. Does anyone know a part number? i was on a site that i was shown by a member on here and it looks like it could be part number 7 on the link below... Also a pic of what the plug looked like!

http://www.marineengine.com/parts/mercury-outboard-parts/500/2858814-thru-4140999-usa/crankshaft-piston-and-connecting-rod

Let me know what you think, could really use some help.

 

[CharlieB]

Re: 1971 50 hp 4 cylinder stalling issue. milky liquid on plug

Those little 'dots' are water mixed with the oil on the plug. The usual suspect is the exhaust side cover gaskets. There are two, an inner plate gasket that keeps the water out of the exhaust and the outer between the inner and outer exhaust plates.

While you have the covers off, carefully check all surfaces for straightness, with no cracks or holes corroded thru the inner plate.

If you opt to use any type of sealant on the inner gasket only use the bare minimum and allow to almost fully dry before assembly as many sealants wet may allow the gasket to 'squeeze' out and tear. Being an inner gasket it cannot be seen during assembly, you won't know it is bad until the water leaks in again, possibly damaging your motor.

 

[oldyeller2011]

Re: 1971 50 hp 4 cylinder stalling issue. milky liquid on plug

Thanks CharlieB. What is the chance that it could be a crack in the motor? I am hopping that it is only a gasket repair. It was weird that it only really stalled when i put it into gear. It seems like its not to hard of a job. Thank you again!

 

[oldyeller2011]

Re: 1971 50 hp 4 cylinder stalling issue. milky liquid on plug

Thanks CharlieB. What is the chance that it could be a crack in the motor? I am hopping that it is only a gasket repair. It was weird that it only really stalled when i put it into gear. It seems like its not to hard of a job. Thank you again!

One other thing charlie! in the link below in the picture are the gaskets your talking about number 18 and 20? and the plate that you said to check number 19?

http://www.marineengine.com/parts/mercury-outboard-parts/500/2858814-thru-4140999-usa/end-caps-manifold-and-exhaust-covers

Thank you for all your help again!

 

[CharlieB]

Re: 1971 50 hp 4 cylinder stalling issue. milky liquid on plug

Correct

Be very careful with those cover bolts, just yanking on a wrench is a sure way to break many of them off. Dissimilar metals corrode and almost weld them together. If you have access to a small torch, heat each head red hot and allow to fully cool, smack each head a couple of times straight on, the shock will help break the corrosion in the threads. Squirt with PB Blaster or equiv penetrant, gently 'rock' the bolt, when it does begin to turn, even the slightest, stop, turn it back IN that same amount. Add more penetrant, work the bolt in/out, gradually increasing how far it turns, always adding penetrant.

I've had much success using a 1/4 inch air gun turned way down, the repetitive 'shocks' of the hammer blows help break the corrosion. Any larger air tool will just break the bolts immediately.

 

[canoemang]

Re: 1971 50 hp 4 cylinder stalling issue. milky liquid on plug

Ive taken the advice above from Charlie and used the heat wrench and PB and im 2 for 2 water jackets with no broken bolts. People get impatient and try to rush through it and snap them.

take your time.. if one feels snugs up while loosing it, move on to the next one. I had a bolt i knew was gonna snap and after the 2nd day of heat and loose/tight i got it!!!

 

[Faztbullet]

Re: 1971 50 hp 4 cylinder stalling issue. milky liquid on plug

A lower crank seal will do this also.....

 

[oldyeller2011]

Re: 1971 50 hp 4 cylinder stalling issue. milky liquid on plug

CharlieB you where right! I found a small hole size of a pen tip in it. I have pictures. I hope i wasn't to late. i know i had 105-110 in the cylinder it was leaking in. But to me it looks much worse.. from the pictures you will see.. I am not going to rebuild as I hope it will still last me a year or two like this. I did break 4 bolts. If i have to ill take to a machine shop. But i think I can I maybe able to get them out with some pliers. Also I am wondering If i should just patch the hole. because it looks like someone else did and if i do it thick enough with a welder it may be okay?

Let me know what you guys think. I also was trying to get to the lower seals while i had it out but it looks like I may need a puller to get to them? am I correct?


Thanks again CharlieB and everyone else!

 

[oldyeller2011]

Re: 1971 50 hp 4 cylinder stalling issue. milky liquid on plug

Pictures of the hole I found. It was in the small chamber that makes an L.

 

[oldyeller2011]

Re: 1971 50 hp 4 cylinder stalling issue. milky liquid on plug

.
..

 

[canoemang]

Re: 1971 50 hp 4 cylinder stalling issue. milky liquid on plug

I would not attempt a repair on it.. Find a new/used plate.

That cylinder looks like it has cracks also and i would not run it that way...